Bis(pyrazol-1-yl)acetates as tripodal “scorpionate” ligands in transition metal carbonyl chemistry: syntheses, structures and reactivity of manganese and rhenium carbonyl complexes of the type [LM(CO) 3] (L=bpza, bdmpza)

Abstract

The coordination of the ligands bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza) and bis(pyrazol-1-yl)acetate (bpza) to Group VII metal carbonyls has been investigated. The compounds [LM(CO) 3], where M=Mn, Re and L=bpza, bdmpza ( 2a– 3b), have been synthesised. The new complexes [(bdmpza)Mn(CO) 3] ( 2b), [(bpza)Re(CO) 3] ( 3a) and [(bdmpza)Re(CO) 3] ( 3b), and bis(pyrazol-1-yl)acetic acid ( 1a) have been characterised by single-crystal X-ray analyses. Based on IR-spectroscopic and structural data the electronic properties of these ligands are compared with those of Tp, Tp Me 2 , Cp and Cp*. The reaction of [(bdmpza)Re(CO) 3] ( 3b) with NOBF 4 afforded [(bdmpza)Re(CO) 2(NO)]BF 4 ( 4).